Heating coagulation therapies are methods of thermally treating a malignant tumor such as a prostrate cancer, a liver cancer, and a breast cancer; and a diseased part such as a uterine myoma and a prostrate hypertrophy by radiating a strong converging ultrasound beam radiation or an electromagnetic wave such as an RF (Radio Frequency) beam and a microbeam. These treatment methods enable a therapy without an incision of a body surface, and therefore, their application to clinical practice is enlarging as a minimally invasive treatment method.
Furthermore, an ultrasound imaging method makes it possible to observe a tomogram of a living body in real time; however, it images only a region of not less than a boiling point, and it is difficult to image a protein denaturation region of 60 Celsius degrees to less than 100 Celsius degrees generated by the heating coagulation therapies.
In order to solve the problem, there are disclosed an elastic modulus imaging method of using a pressurizing method and a radiation region imaging method of using a radiation force of a strong converging ultrasound beam.
The elastic modulus imaging method is a method of pressurizing a body surface from outside while imaging an ultrasound tomogram, estimating a displacement degree according to a correlation between received signals of different time phases, and presuming that a region where the displacement is large is a soft region and that a region where the displacement is small is a hard region (non patent document 1). Furthermore, with respect to the radiation region imaging method of using the radiation force, if a temperature of a radiation region rises by an ultrasound treatment, an absorption coefficient of an ultrasound of the region selectively becomes large compared to a surrounding tissue; therefore, the radiation force selectively acts only on the region of a temperature rise, and the region is moved and displaced toward a direction away from a therapeutic transducer; therefore, the radiation region imaging method is a method of detecting the displacement region (patent document 1).    Non patent document 1: 1999 IEEE ULTRASONICS SYMPOSIUM p. 1631 Elasotgraphic Imaging of thermally ablated tissue in vitro M. M Doyley, I. C. Bamber, L Rivens, N. L. Bush, and G. R. ter Harr    Patent document 1: Specification of U.S. Pat. No. 6,488,626